Portsmouth, RI climate
Portsmouth has chilly, snowy winters and pleasant summers, with plenty of rain. A typical July afternoon reaches 81°, a January night drops to 23°, and about 37 inches of snow falls in a normal winter.
NOAA 1991-2020 climate normals Updated once a decadeWhat a year in Portsmouth feels like
Winter
Spring
Summer
Fall
Portsmouth weather by month
Average highs, lows, rain and snow for every month, from NOAA’s 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 38° | 23° | 3.9" | 10.3" | 11 | 8 | 22° – 38° |
| February | 40° | 24° | 3.5" | 10.5" | 10 | 8 | 20° – 39° |
| March | 47° | 31° | 4.9" | 6.4" | 12 | 4 | 33° – 45° |
| April | 57° | 39° | 4.3" | 0.6" | 12 | 0 | 44° – 53° |
| May | 67° | 49° | 3.5" | 0 | 12 | 0 | 52° – 62° |
| June | 75° | 58° | 3.7" | 0 | 11 | 0 | 64° – 70° |
| July | 81° | 65° | 3.2" | 0 | 9 | 0 | 69° – 77° |
| August | 80° | 64° | 3.7" | 0 | 9 | 0 | 69° – 76° |
| September | 74° | 57° | 3.9" | 0 | 9 | 0 | 63° – 69° |
| October | 63° | 47° | 4.5" | 0.2" | 10 | 0 | 51° – 61° |
| November | 53° | 37° | 4.1" | 1.0" | 10 | 1 | 41° – 49° |
| December | 44° | 29° | 4.7" | 7.6" | 12 | 4 | 30° – 47° |
| Year | 60° | 44° | 47.8" | 36.6" | 127 | 25 |
“Wet days” have at least 0.01" of rain or melted snow. “Snow on ground” counts days with 1" or more. The 30-year range is the coldest and warmest that month’s average temperature got between 1991 and 2020.
Rain and snow in Portsmouth
Portsmouth gets 48 inches of rain and melted snow a year. March is the wettest month and July the driest. Rain or snow falls on about 127 days a year. Snow covers the ground about 25 days of the year.
About 199 frost-free days a year
In half of years the last 32° night comes by April 11 and the first one by October 30. That leaves about 199 frost-free days for gardens, longer than 72% of U.S. towns.
Heating and cooling a home in Portsmouth
Engineers use “degree days” to estimate how hard a furnace or air conditioner works. In Portsmouth, 87% of that work is heating and 13% is cooling, so the furnace matters far more than the air conditioner.
Degree days measure how far each day’s average temperature falls below or rises above 65°, added up over a year. Source: NOAA station normals.
Portsmouth and its neighbors
Portsmouth borders 8 towns with climate data. January nights across them vary by 1.0°. Warwick has the coldest January nights (23°) and Barrington the hottest July afternoons (82°). Portsmouth’s January low is 23° and its July high 81°.
Temperatures and rain come from NOAA’s 5 km grid, so each town gets its own value.
How Portsmouth compares
Compared with every U.S. town and city on TownTapestry, each counted once.
Warmer than it used to be
The last 30 years in Portsmouth averaged 2.1° warmer than the 1900s. The biggest change is in December (+3.4°). The shift is larger than in 95% of U.S. towns.
Change by month1991–2020 average minus 1901–2000 average, at Portsmouth’s spot on NOAA’s grid
How much a month can swing
A normal is an average, and real years wander around it. February swings the most: between 1991 and 2020 its average temperature ranged from 20° to 39°. June is the most reliable, staying within 6°.
Common questions about Portsmouth’s climate
What is the coldest month in Portsmouth?
January, with a typical high of 38° and a low of 23°.
What is the hottest month in Portsmouth?
July, with a typical high of 81° and a low of 65°. About 12 days a year reach 90°.
How much snow does Portsmouth get?
About 37 inches in a normal winter, most of it in February.
When is the first frost in Portsmouth?
In half of years the first 32° night comes by October 30, and the last spring frost by April 11.
What is the rainiest month in Portsmouth?
March, with 4.9 inches of rain and melted snow. The year totals 48 inches.
Temperatures and rainfall come from NOAA’s gridded climate normals for Portsmouth itself (about a 3-mile square). Snow, frost dates and day counts come from NOAA’s weather station at Providence T F Green Airport, RI (8 mi) away. Normals are 30-year averages, not a forecast. Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000.